Safety appliance for electric switches



Dec. 18 1923.

M. MURRAY SAFETY APPLIANCE FOR ELECTRIC SWITCHES Filed Aug. 19, 1918Patented Dec.'18, 1923..

UNITED sures 1,477,841 PATENT OFFICE.

MICHAEL MURRAY, OF CHICAGO, ILLINOIS.

SAFETY APPLIANCE FOR ELECTRIC SWITCHES.

Application filed August 19, 1918. Serial No 250,442.

To all whom it may concern:

.Be it known that 1, MICHAEL MURRAY, a citizen of the United States,residing in Ohicago, in the county of Cook and State of Illinois, haveinvented a new and useful Imother places using relatively high current,

although 'it will be manifest that the invention may be used toadvantage with switches in any circuits where it is desired to preventmanipulation of the switch under predetermined conditions.

In industrial plants and factories using electric power, it notinfrequently happens that an operator or workman in making repairs oradjustments requires that the condition of the circuit be maintained. Itmay be that it is necessary that current be continually applied to aparticular apparatus while the repairs or adjustments are being made orthat the circuit be left open. Sometimes after a workman has arrangedthe switch in the position he desires and gone to the apparatusrequiring his attention at some distance from the switch, anotheremployee may inadvertently or maliciously change the arrangement of theswitch notwithstanding the necessity of the previously arrangedcondition, with resulting injury to theapparatus or to the workmanworking upon it.

I am aware that in the past, arrangement has been made to lockt heswitch arm in either opened or closed position or both by the use of apadlock. This method of protecting the workman has been foundineffective for the reason that the padlocks being readily stolen orlost soon disappear and for the further reason that the ordinaryemployee or workman does not usually go to the trouble of firstarranging the switch as he may desire it and then attaching the padlock.

A principal object of my present invention is the provision of asafety'appliance for electric switches which may be readily arranged bya workman to maintain the switch in desired electrical condition andwithout requiring more than a mere opening of a housing door orequivalent single action.

The construction and arrangements of the parts of an appliance in whichmy invention may be embodied is preferably such that after theestablishment ofsuch condition rearrangement of the device is impossiblewithout a full realization of the fact that it has been previouslyarranged intentionally and probably-for a specific purpose.

A further object of the invention is a pro vision of such an appliance,adapted by its construction to enforce a regulation to the effect thatrearrangement can only be permitted after a report to and under theauthorization of proper authority.

, A still further object of the invention is a provision of a device ofthe character described, which will preven .a person manipulating aswitch from ing injured or burne by a flash caused by opening or closingthe switch or by blowing of a fuse.

Another object of the invention is the provision of an appliance of thecharacter described, which will be strong and durable in use and whichmay be cheaply manufactured and readily installed or substituted for theswitch box already generally in use.

Numerous other objects and advantages of the invention will be apparentfrom the following description which, taken in connection with theaccompanying drawing,

illustrates a preferred embodiment thereof.

On the drawing,

Figure 1 is ahorizontal section through an apparatus embodying myinvention;

Fig. 2 is a front elevation of the same, the door being open-as shown insection;

Fig. 3 is a section taken substantially on the line33 of Fig. 1; and

Fig. 4 is a detail of certain parts.

For the purpose of illustrating my invention, I have shown on the drawina conventional electric switch comprising the usual base 10, switchblades 11, operating handle '12 and feeding and delivery wire 13. Thesafety appliance in the form shown on the drawingcomprises a metalswitch box having side walls 14, rear wall 15, upon or through which thebase 10 is secured, top and bottom walls 16, and the closure or door 17spring-hinged along one edge 18 in the present instance.

It is intended that the switch shall only be operated when thedoor is infully closed position and in order that it may be then manipulated Iprovide a crank rod 19 having alined bearings 21 in the sides of thehousing and having also an offset part 22 disposed within the housing.This part 1s connected by a yoke or strap 23 with the switch handle 12.

The portion of the rod 19, which extends outside the casing or housing,is bent up at 24L and may be provided with a handle 25. Swinging of thehandle will therefore pro duce opening and closing swinging movement ofthe switch blades. Means are provided to be projected across the path ofmovement of the handle of the switch except when the door is fullyclosed, and this means in the present instance consists of anobstruction formed of a metal plate 26 of box-like form, "which. isfastened upon a slide bar 27, mounted in bracket straps 28 fixed on theinside of the housing sidewalls. This bar is connected by a link 29 witha lug 31 on the door, so that as soon as the door starts to open link 29pulls the slide bar 27 toward the left v(viewing Fig. 1) from theposition shown in dotted lines. When the door is fully opened the slidebar has moved the obstruction to the position shown in full lines.

A latching device is provided to lock the slide bar against returnmovement after the door has been once fully opened. This'da vicecomprises in the present instance a latch lever 32, pivoted at 33 on theleft hand bracket 28 and having a hooked end 34 adapted to engage in aslot or recess 35 provided near the end of the slide bar 27. A

spring 36 pulls upwardly on the latch and holds it in engaged position.The latch lever 32 has a tail 37 positioned. just above a key hole 38 inthe forward side of the bracket strap 28. so that release of the sidebar to permit closing of the door and manipulating of the switch canonly be accomplished through the use of a suitable key. A casing plate39' is preferably disposedover the forward face of the bracket and maydesired entirely encase the bracket.

It will be manifest from the foregoing description that a workman,desiring to repa1r a line shaft or other piece of mechamsm ordinarilyonly to open the switch and then open the door its full distance to lockthe switch in opn position, cutting off the power to the deemedapparatus, or if the adjustment or repairs require the" continuedpresence of the current he mayiopen the door to its full extent lockingthe switch in closed position.

It is intended that Where safety appliances embodying iny invention areused the key to the latch ,will be in the hands and only 111' the handsof some person of competent authority as for example the foreman or shopsuperintendent sothat further madriven by electricity, has

flash, incidental to the closing or opening of the switch, burning anemployee and in view of the fact that the switch can only be manipulatedwhen the door is closed there is little likelihood of the switch beingleft open except by deliberate intent for under such conditions theswitch cannot be shifted. The construction of the appliance thereforeinsures that the door be left closed unless it be deliberately leftopen.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing description, and it will beapparent that various changes may be made in the form, construction andarrangement of the parts without departing from the spirit and scope ofthe invention or sacrificing all of its material advantages, the formhereinbefore described being merely a preferred embodiment thereof.

I claim:

1. A safety appliance for electric switches, comprising a switch housinghaving a door closing a chamber containing a switch, and meansoperatively connected with the door, for preventing manipulation of theswitch except when the door is in completely closed position, said meansbeing adapted to be automatically locked in obstructing position whenthe door is moved to a predetermined point.

2. A. safety appliance for electric switches comprising a housing, adoor for closing same, a switch mechanism mounted within said housing, amovable member acting under the influence pf the door for moving intothe path of the switch arm, and means locking the parts in assumedrelation when the door is moved to predetermined position, said meansrequiring unlocking by a key or other instrument not attached to theapparatus.

3. A safety appliance for electric switches, comprising a housing, an.obstruction projectable into the path of the switch arm, and meansautomatically locking the door in a predetermined position with anobstruction across the path of movement of .the switch arm.

4. A safety appliance for electric switches, comprising a housing, adoor in said housing, and an obstruction projectable upon openingmovement of the door into the path of a switch arm within the housingand connected with the door,and means of latching the door in fully openposition .with the obstruction across the path of the switch arm.

5. A safety appliance for electric switches, comprising a housing, adoor in said housing, and an obstruction projectable upon openingmovement of the door into the path of a switch arm within the housingand connected with the door, and means of latching the door in fullyopen position with the obstruction across the path of the switch arm,said obstruction being moved by the door in its initial opening movementinto operative position.

6. A safety appliance for electric switches comprising a single chamberhousing containing switch mechanism, a door for said housing, and meansmovable by the door for controlling manipulation of the switch andlocking the door in open position, said means requiring releasethereafter by a separate key or implement unattached to the door orhousing.

7. safety appliance for electric switches comprising a housing having adoor, means extending without the housing for manipulating the switch,means for rendering said switch manipulating means inoperative when thedoor of the housing is opened, and a keycontrolled lock automaticallyoperable to lock the door when it arrives at fully open position,thereby positively preventing operation of said switch manipulatingmeans.

8. A safety appliance for electric switches,

comprising a switch housing, a door closing said housing, means operableby the opening of the door to obstruct closing movement of the switch,and means automatically locking the door in a predetermined positionwith said obstructing means across the path of closing movement of theswitch.

MICHAEL MURRAY.

